Assembling arrays of small particles using an atomic force microscope to define ferroelectric domains

Abstract

A method of assembling arrays of small particles or molecules using an atomic force microscope to define ferroelectric domains includes depositing a ferroelectric thin film upon a substrate forming workpiece, then using an atomic force microscope having a conductive, tip for generating a pattern on this thin film to define desired nano-circuit patterns. Next, exposure of this thin film to a solution containing chemical species which selectively adsorb or accumulate under the influence of electrophoretic forces in selected regions of this thin film.

What is claimed is:  
     
       1. A method for assembling arrays of small particles using an atomic force microscope (AFM), said method comprising: 
       depositing a ferroelectric film layer on a substrate;  
       tracing a pattern on said ferroelectric film with said AFM thereby leaving a traced pattern of charged and uncharged domains on said film; and  
       exposing said ferroelectric film to a composition having nanosized particles, said particles coated with an organic species that selectively accumulate in said traced pattern of said film.  
     
     
       2. The method of  claim 1 , wherein said exposure of said film includes initially selecting said composition that comprises a solution that includes chemical species of nanosized dielectric particles selected from a group consisting of metallic and semiconductor materials. 
     
     
       3. The method of  claim 1 , wherein said tracing is provided by an X-Y motor driven stage for maintaining relative positioning between a tip member of said AFM and said substrate. 
     
     
       4. The method of  claim 3 , wherein said tracing includes selection of a tip that is a conductive tip member comprising a material that is selected from the group consisting of silicon and tungsten. 
     
     
       5. The method of  claim 3 , wherein said tracing includes scanning with a negative, positive and neutral bias by said tip forming a requisite pattern on said substrate by remnant polarization in ferroelectric domains under said tip. 
     
     
       6. The method of  claim 1 , wherein said coating of said substrate includes selecting said film material having a small coercive field. 
     
     
       7. The method of  claim 6 , wherein said selection of said film is from a group consisting of Pb(Zr x Ti 1−x )O 3  (PZT); Bi 4 Ti 3 O 12 ; SrBiTaO 3 ; SrBi 2 NbTaO 9 : SrBi 2 Ta 2 O 9 ; YMnO 3 ; and Sr 1−x Ba x Nb 2 O 6 . 
     
     
       8. The method of  claim 1 , wherein said exposing of said ferroelectric film to a composition includes selecting an electrostatically charged composition which comprises a solution containing chemical species that selectively accumulate by electrophoretic forces in said traced patterns of said ferroelectric film. 
     
     
       9. The method of  claim 1 , wherein said exposing of said ferroelectric film to a composition includes selecting a highly polarizable composition that comprises a solution containing chemical species that selectively accumulate by dielectrophotetic forces in said traced patterns of said film. 
     
     
       10. A method for assembling strays of small particles using an atomic force microscope (AFM), said method comprising: 
       depositing a ferroelectric film layer on a substrate;  
       tracing a pattern on said ferroelectric film with said AFM thereby leaving a traced pattern of charged and uncharged domains on said film;  
       exposing said ferroelectric film to a composition having nanosized particles, said particles coated with an organic species that selectively accumulate in said traced pattern of said film; and  
       wherein said method forms conductive nanowires in a nano-sized circuit by heating said deposited nanosized particles so as to make an electrical contact.  
     
     
       11. The method of  claim 9 , wherein said method forms conductive leads in a nano-sized circuit by depositing additional metal by selective chemical vapor deposition. 
     
     
       12. A method of producing three-dimensional submicron heterostructures on a workpiece, said method comprising: 
       tracing a modulated pattern on a ferroelectric film layer on said workpiece by an atomic force microscope; and  
       adsorbing a chemical species on said pattern, wherein said tracing creates a polarization template on said ferroelectric film.  
     
     
       13. The method of  claim 12 , wherein said adsorbed chemical species at said selected regions of said workpiece are is a material characterized by properties that allow fusing by activated polymerization by a method selected from a group consisting of thermal, photochemical and chemical initiation. 
     
     
       14. The method of  claim 13  further comprising: 
       providing a second workpiece;  
       transferring said adsorbed chemical species at said selected regions of said workpiece to said second workpiece; and  
       treating said adsorbed chemical species to enhance adhesion of said adsorbed chemical species to said second workpiece.  
     
     
       15. The method of  claim 14  further comprising repeatedly using said first workpiece as a template. 
     
     
       16. The method of  claim 12 , wherein said tracing includes AFM scanning, with a negative, positive and neutral bias, a tip of said AFM forms said pattern on said substrate by remnant polarization in a ferroelectric domain in said film. 
     
     
       17. The method of  claim 16 , wherein said tracing is provided by an X-Y table for maintaining relative positioning between said tip of said AFM and said substrate. 
     
     
       18. The method of  claim 17 , wherein said tracing includes selection of a tip comprising a material selected from the group consisting of silicon and tungsten. 
     
     
       19. The method of  claim 12 , wherein said coating of said substrate includes selecting said film material having a small coercive field. 
     
     
       20. The method of  claim 19 , wherein said selection of said film is from a group consisting of Pb(Zr x Ti 1−x )O 3  (PZT); Bi 4 Ti 3 O 12 ; SrBiTaO 3 ; SrBi 2 NbTaO 9 : SrBi 2 Ta 2 O 9 ; YMnO 3 ; and Sr 1−x Ba x Nb 2 O 6 . 
     
     
       21. A method for assembling arrays of small particles using an atomic force microscope (AFM), said method comprising: 
       depositing a ferroelectric film layer on a substrate;  
       tracing a pattern on said ferroelectric film with said AFM thereby leaving a traced pattern of charged and uncharged domains on said film; and  
       exposing said ferroelectric film to a composition having nanosized particles, said particles coated with an organic species that selectively accumulate in said traced pattern of said film, wherein said exposure of said film includes initially selecting said composition that comprises a solution that includes chemical species of nano sized dielectric particles selected from a group consisting of metallic and semiconductor materials.  
     
     
       22. The method of  claim 21 , wherein said tracing is provided by an X-Y motor driven stage for maintaining relative positioning between a tip member of said AFM and said substrate. 
     
     
       23. The method of  claim 22 , wherein said tracing includes selection of a tip that is a conductive tip member comprising a material that is selected from the group consisting of silicon and tungsten. 
     
     
       24. The method of  claim 21 , wherein said coating of said substrate includes selecting said film material having a small coercive field. 
     
     
       25. The method of  claim 24 , wherein said selection of said film is from a group consisting of Pb(Zr x Ti 1−x )O 3  (PZT); Bi 4 Ti 3 O 12 ; SrBiTaO 3 ; SrBi 2 NbTaO 9 : SrBi 2 Ta 2 O 9 ; YMnO 3 ; and Sr 1−x Ba x Nb 2 O 6 . 
     
     
       26. The method of  claim 21 , wherein said exposing of said ferroelectric film to a composition includes selecting a highly polarizable composition that comprises a solution containing chemical species that selectively accumulate by dielectrophotetic forces in said traced patterns of said film. 
     
     
       27. A method for assembling arrays of small particles using an atomic force microscope (AFM), said method comprising: 
       depositing a ferroelectric film layer on a substrate;  
       tracing a pattern on said ferroelectric film with said AFM thereby leaving a traced pattern of charged and uncharged domains on said film;  
       exposing said ferroelectric film to a composition having nanosized particles, said particles coated with an organic species that selectively accumulate in said traced pattern of said film, wherein said exposure of said film includes initially selecting said composition that comprises a solution that includes chemical species of nanosized dielectric particles selected from a group consisting of metallic and semiconductor materials; and  
       wherein said method forms conductive nanowires in a nano-sized circuit by heating said deposited nanosized particles so as to make an electrical contact.  
     
     
       28. The method of  claim 27 , wherein said method forms conductive leads in a nano-sized circuit by depositing additional metal by selective chemical vapor deposition.